Résumé
Aim: Climatic variation may affect plant-pollinator interaction potential by shaping intra-annual patterns of flowering and foraging, thereby altering the windows of temporal overlap between partners. We examined whether spatial variation in temperature and precipitation predicted plant-pollinator interaction potential across a dryland ecosystem elevational gradient spanning desert to pine forest.Location: Five sites representing distinct communities along a 2230 m elevational gradient in the Santa Rosa Mountains, CA, USA.Time Period: February to August in 2021 and 2022.Major Taxa Studied: Eighty-two flowering plant species and 386 pollinator species.Methods: Using data on flowering phenology and pollinator visits to flowers, we tested whether temperature and precipitation explained variation in plant-pollinator interaction potential as quantified in two ways: first, whether pairs of species flowered/foraged in the same year and site (binary temporal co-occurrence) and second, the magnitude of overlap in their phenological distributions (phenological synchrony).Results: Plants and pollinators showed reduced temporal co-occurrence and synchrony under warmer temperatures. Additionally, phenological synchrony between pollinators and flowers was negatively related to precipitation. However, shorter pollinator foraging periods translated to increased synchrony with flowering plants, while shorter flowering periods were associated with decreased synchrony with pollinators.Main Conclusions: Our findings show that warmer temperatures across the gradient were associated with lower likelihood of temporal co-occurrence in flowering and pollinator visitation, as well as lower synchrony in the phenologies of these mutualistic partners. In addition, lower synchrony was associated with higher levels of precipitation. Although greater pollinator synchrony with flowers under drier conditions may buffer short-term negative effects of greater aridity, increasing climate extremes and shifts in precipitation patterns could further reduce plant-pollinator synchrony in the future. Leveraging the spatial variation in climate along an elevational gradient, our findings indicate that climatic conditions influence the timing and duration of plant-pollinator interactions in arid ecosystems, suggesting that climate change may alter the temporal structure of these communities.